Many boats and other watercraft are propelled by one or more propellers that are driven by one or more inboard or outboard engines or a stern drive system. Each propeller typically has three or four blades, but may have as few as two or more than four. The base of each blade is mounted at an angle, or pitch, relative to a radial plane transverse to the axis of rotation of the propeller shaft. Some propellers have blades with a variable pitch, so that the pitch can be adjusted to provide increased efficiency, faster acceleration, or other desired performance characteristics at a wider range of speeds than blades having a fixed pitch. The variable pitch mechanism may be either manually actuated or regulated by an electronic control unit (ECU) based on one or more operating parameters of the watercraft such as vehicle speed and propeller rotation speed.
From time to time, the user of a watercraft may desire to slow down the watercraft quickly, for example to avoid striking an obstacle in the water. One method of slowing down a watercraft is to manually move the throttle actuator to an idle speed position, disengage the engine from the propeller or turn the engine off completely, and allow the friction created by the hull in the water to slow the forward motion of the watercraft. However, the user may wish to slow down the watercraft more quickly.
The user of a watercraft may alternatively attempt to rapidly decelerate the watercraft by quickly moving the throttle lever from a forward thrust position to a reverse thrust position. This method may cause damage to various components of the watercraft, particularly if the engine speed is relatively high. In particular, reversing the direction of rotation of the propeller at high speeds may cause stress on the propeller blades and hub, and the shift from forward gear to reverse gear at high engine speeds may damage the transmission gears. In addition, it may be difficult for the user to control the degree of deceleration of the watercraft. Furthermore, steering to avoid an obstacle with thrust directed in the reverse direction may be difficult or counter-intuitive to some users.
Therefore, there is a need for a watercraft providing an alternative system for slowing down.
There is also a need for a method of causing the deceleration of a watercraft having these properties.